Will, Scion of Peace + Whitemane Lion + Phyrexian Altar + Blessed Sanctuary

Will, Scion of Peace

Whitemane Lion

Phyrexian Altar

Blessed Sanctuary

How it works

1. Activate Will by tapping it, reducing the cost of all white and/or blue spells you cast this turn by at least 1.
2. Cast Whitemane Lion by paying due to Will's ability.
3. When Whitemane Lion enters the battlefield, it and Blessed Sanctuary trigger.
4. Resolve the Whitemane Lion trigger, returning it to your hand from the battlefield.
5. Resolve the Blessed Sanctuary trigger, creating a 2/2 Unicorn creature token.
6. Activate Phyrexian Altar by sacrificing the Unicorn, adding .
7. Repeat from step 2.

By leveraging Will, Scion of Peace, you can tap it to dramatically discount the cost of white spells based on the life you've gained, allowing you to cast Whitemane Lion for a mere single white mana. As the Lion repeatedly enters the battlefield, Blessed Sanctuary not only safeguards your board from noncombat damage but also generates a 2/2 Unicorn token on each iteration. You can then feed these tokens directly into Phyrexian Altar to harvest the exact mana needed to recast the Lion, creating an endlessly self-sustaining loop.